A hand-held weapon such as a rifle, pistol, or directed-energy device is aimed by pointing the barrel of the weapon at a target. To aid in the pointing, a sight is usually provided. “Iron” sights utilize fixed mechanical structure on the top of the barrel to aid in aligning the barrel toward the target. Laser sights project a laser beam that is placed on the target to aim the weapon. Telescopic sights use optics to view the image of the target, and typically enlarge the image of the target. The present approach is concerned with such telescopic sights.
The telescopic sight includes a sighting reference feature such as a cross hair. The sighting reference feature allows the visual sighting by the user of the weapon to be brought into correspondence with the impact point of the projectile. During the calibration of the sight, the position of the sighting reference feature is adjusted to achieve a correspondence between the aiming point of the sighting reference feature and the impact point of the projectile. In telescopic sights that are to be used in reduced-light applications, the sighting reference feature is typically illuminated so that it may be clearly viewed against the primarily reduced-light field seen through the sight.
Experience has shown that different types of sighting reference features are most advantageously used in particular situations. For example, for short-range, rapid-fire aiming, typically where the target is at a distance of less than about 200 meters, a single dot (traditionally a red dot) sighting reference feature gives the best results because of its simplicity and quick target acquisition, and because the user is not distracted by any reference feature other than the single dot. For longer-range, lower-firing-rate aiming, typically where the target is at a distance of more than about 200 meters and more-precise aiming is required, a sighting reference feature such as a cross hair with ranging lines gives greater accuracy, because the user can more readily take into account the drop of the projectile over the greater distance and also windage effects. In this long-range situation, the single dot used for close-in aiming is a distraction, and in a short-range situation the cross hair is a distraction.
A weapon that is to be used in both shorter-range and longer-range applications, and in both daylight and reduced-light applications, would desirably include two or more types of sighting reference features. The type of sighting reference feature would be selectively visible to the user of the weapon. There is a need for such a sighting device, which is not currently available. The present invention fulfills this need, and further provides related advantages.